In general, the present invention is directed to a process for improving cotton fibers and textile products containing cotton fibers by, for example, making them resistant to cross-staining. In particular, the present invention is directed to an anionic treatment process for cotton fibers that makes the fibers repel anionically-charged dyes and auxiliaries or attract cationically charged dyes and auxiliaries.
The problem of cross-staining between cotton fabrics during laundering and processing is a significant household and textile problem. Cross-staining relates to the transferring of dye that may occur between fabrics under either wet or dry conditions while fabrics are being manufactured, processed or laundered. Television commercials are aired daily for expensive detergents meant to minimize cross-staining. In fact, much advertising and product manufacturing are devoted to this common annoyance. The detergents that advertise colorfastness are designed to approach the problem of cross-staining through the use of dye antiredeposition agents that are incorporated into their formulas. These antiredeposition agents, however, add expense to the detergents and are not fully effective in preventing cross-staining. Thus, a method of preventing dye transfer without relying on the use of detergents would prove to be both practical and economical.
The dye transfer between cellulosic fabrics, such as cotton fabrics, occurs when fabrics are laundered or processed in the same bath. Dye transfer occurs because cellulosic fibers have a mild attraction for anionic classes of dyes, which are the majority of the dyes now employed to dye cotton and other cellulosic fabrics and blends. Dyes are made to be anionic or negatively charged so that they will benefit from water solubility. Such classes of dyes include reactives, directs, acids, and the like. A primary example of this dye transfer is the staining of the white pockets in blue jeans during garment manufacture and during laundering. The anionic leuco form of the indigo dyes in the blue jeans are absorbed by the undyed cotton fibers in the pockets because of their chemical attraction to one another.
An even more well-known example is the transfer of dyes between dark-colored garments and white or light-colored garments during the laundering process. The loosely-held anionic dyes in the fibers of the dark-colored garments stain the white or light-colored garments. This dye transfer may adversely affect white or light-colored garments. Similarly, striped or patterned garments containing both dark-colored fabric and white or light-colored fabric may experience bleeding of the dark-colored dyes on to the lighter portions because of the attraction of unfixed anionic dyes to the cellulosic fibers in the white or light-colored portions. Therefore, it is evident that weakening this attraction between the anionic dyes and the cotton fibers would provide a solution to the problem of dye transfer.
A need currently exists for a solution to the problem of dye transfer regarding cellulosic fabrics so that the needs for expensive detergents and other methods of colorfastness are eliminated. In particular, a need exists for a process that treats cellulosic fibers in order to permanently increase their anionic character so that these fibers are able to resist anionic dyes that cross stain fabrics. The present invention is directed to a process that meets the above described need.
The present invention recognizes and addresses the foregoing disadvantages and drawbacks of prior art constructions. Accordingly, it is an object of the present invention to provide a process for making cellulosic fibers, such as cotton fibers, and textile products made from the fibers anionic, resistant to cross-staining, and improved as far as hand, appearance, and comfort.
Another object of the present invention is to provide a process for making cotton fibers resistant to cross-staining through a permanent anionic treatment.
Another object of the present invention is to provide a process that not only makes cotton fibers resistant to cross-staining, but also provides the fibers with a greater attraction to cationic fabric softeners and bacteriocides.
It is another object of the present invention to provide a process for treating cotton fibers with a softener that results in a fabric having great softness properties, good durability, and in which the softener is wash resistant.
Another object of the present invention is to provide a process for treating cotton fibers in a manner that permits the fibers to become bonded with bacteriocides at high and effective concentration levels.
Still another object of the present invention is to provide a process for treating cotton fibers or textiles containing cotton fibers with a sulfamate, which increases the anionic charge of the material.
Another object of the present invention is to treat cotton fibers, or textiles made from the fibers, with a pre-formed complex containing sulfamic acid and urea such that a material resistant to cross-staining can be formed at lower temperatures.
It is another object of the present invention to treat cotton fibers, or textiles made from the fibers, with a pre-formed complex containing sulfamic acid and urea, wherein the sulfamic acid is present in a sufficient amount to prevent misting of the urea when the complex is heated.
These and other objects of the present invention are achieved by providing a process for making fabrics containing cellulosic fibers, particularly cotton fibers, resistant to cross-staining. More particularly, the fabrics become resistant to being stained by anionic coloring agents that may undesirably contact the fabric during the manufacture of the fabric or during laundering or some other aqueous process. Furthermore, fibers used in cotton carpeting become resistant to being stained by accidental spillage.
The process includes the steps of providing a fabric containing cotton fibers. The fabric can be pre-dyed and/or can be in a substantially finished state. The fabric is contacted with a solution that includes a pre-formed complex. The complex contains a derivatising agent. For instance, the agent can be sulfamic acid. In addition, the complex can also contain other materials, such as urea.
Once contacted with a derivatising agent contained within the pre-formed complex, the fabric is heated to a temperature sufficient for the agent to react with the cellulosic fibers contained within the fabric. Through this reaction, the anionic charge of the cellulosic fibers is increased for making the fibers more resistant to anionic coloring agents during casual contact. Moreover, the use of a pre-formed complex allows such an anionic charge to be achieved at relatively low temperatures.
Although the combination of sulfamic acid and urea will sulfate cotton, it is but one of several methods according to the present invention of permanently rendering cotton anionic in charge. It is the anionic charge and not the reagents or structure of the anionic derivative that matters, but the negative (anionic) charge itself that is the means of achieving the benefits of this invention.
For most applications, the process of the present invention is used to protect predyed and pre-formed fabrics from staining during consumer laundering. It should be understood, however, that the process of the present invention can also be used to treat fibers themselves prior to being formed into a fabric or garment.
As described above, in one embodiment, the sulfating agent is sulfamic acid. In this embodiment, the sulfating agent can be carefully mixed with an amide of a carboxylic acid, such as urea under controlled conditions, to form a complex prior to being applied as an aqueous solution to the fabric or fibers. It is unknown at this time what type of complex is formed between the sulfating agent and the amide of the carboxylic acid. As used herein, the term xe2x80x9ccomplexxe2x80x9d is intended to cover any chemical association or bond. Urea is not only believed to act as a catalyst, but also protects the fabric from yellowing and from being damaged by heat during sulfation.
In one embodiment, a urea-sulfamic acid complex is formed by mixing sulfamic acid with excess urea in a mole ratio of about 1 mole sulfamic acid to about 6 moles urea. The mixture is then heated in the presence of phosphoric acid such that a complex can be formed. The resulting complex can then be diluted with water. In one embodiment, phosphoric acid remains present in the form of ammonium phosphate in an amount of about 0.2 moles for every 1.0 mole of urea.
Prior to sulfation, the fabric or fibers are dried in order to remove substantially all of any moisture present on the fibers. For example, in one embodiment, the fabric can be dried at a temperature of from about 150xc2x0 F. to about 200xc2x0 F. prior to sulfation.
It should be understood, however, that other concentrations, parameters, and reagents can be employed to render cellulosics, such as cotton, anionic. Other reagents include SO3, P2O5, sodium chloroacetate, 115% polyphosphoric acid, maleic anhydride, the reaction product of epichlorohydrin and sodium sulfite or bisulfite, vinyl sulfonate, the condensate of DMDHEU and sulfite, etc.
After drying, the fabrics or fibers can also be cured. When curing a fabric treated with a complex of the present invention, misting can often occur, especially when the complex is heated to temperatures greater than or equal to about 340xc2x0 F. In one embodiment, to prevent such misting, additional amounts of sulfamic acid can be applied to compensate for any free urea present within the complex. It has been discovered that when additional sulfamic acid is used in a complex of the present invention, a non-volatile salt can form which prevents misting, while still allowing the urea and sulfamic acid to remain functional in the anionic-generating process.
Besides preventing cross-staining, it has been discovered that negatively charged cotton is also able to attract positively charged auxiliaries such as basic dyes. When sufficient negative charge is affixed to cotton, significant levels of basic dyes will readily exhaust.
Negatively charged cotton or more simply anionic cotton will also attract significant amounts of cationic softeners such as fatty quaternaries and amino siloxanes. Further, it has been discovered that once the softener is applied to the cotton, the softener can withstand repeated wash cycles. The level of negative charge will control the amount exhausted. Therefore, by controlling the level of anionic charge, one can control the degree of softener and hence softness of the garment. The ability to achieve maximum softness at low temperatures and very short exhaust cycles (3-5 minutes) has never been achieved prior to this invention.
Cationic biocides can also be exhausted at higher levels than typically achieved on untreated cotton and at levels where more significant efficacy can be achieved.
Anionic cotton will afford garments with greater loft and better smoothing properties (anti-wrinkling). This is because of charge repulsion. With anionic groups, charge repulsion can be a significant force pushing the like charges to repel each other and achieving a farthest separation possible between the fibers resulting in a smoother fabric. Fibrils in the yarns are also repelled from each other and this results in greater loft or bulk.
For these reasons, anionic cotton has a better feel (hand) than untreated fabric even without softeners. This is because the fibrils and yarns are more uniform and bulkier affording a smoother more desirable surface that can be felt and appreciated by the consumer. This is especially evident in loosely constructed fabrics.
The process of the present invention can also be used to treat carpet materials to make them resistant to staining by anionic agents. For instance, carpet materials containing cellulosic fibers, such as cotton fibers, can be sulfated as described above.
Other features of anionic cotton produced according to the present invention are that fabrics made from the cotton have enhanced wrinkle recovery caused by the negative charge repulsion electrostatic effect. For instance, it has been discovered that cotton treated with excess sodium chloroacetate or sulfamic/urea complexes allowed to dry in a smooth wrinkle free state will reorient itself when redried in a tension free environment. In this case, we believe that the negative charges on the cotton repel each other and prefer to orientate back to the most favored positions, which results in smoothing.
For the same reason, the fibrils that make up the yarns when treated repel each other in the resulting fabric increasing loft and resulting in a more open construction that exhibits a more acceptable hand (feel) and transports moisture more easily resulting in greater comfort.
Other objects, features, and aspects of the present invention are discussed in greater detail below.
The present invention is generally directed to a process which permanently increases the anionic charge of cellulosic fibers, particularly cotton fibers, so that the treated fibers resist being cross stained by anionic dyes. As used herein, derivatising cellulosic fibers refers to a process by which the anionic charge of a cellulosic material becomes permanently increased through the formation of a chemical bond, such as a covalent bond, between the cellulosic material and a derivative, which can be a negatively charged ion. When derivatising cotton fibers according to the present invention, an ester linkage is formed between the derivative and the cotton material.
The anionic treatment process of the present invention is generally accomplished by derivatising the cellulosic fibers in a manner that increases the negative charge of the fibers an amount sufficient for the fibers to repel anionically charged dyes. The treated cellulosic fibers and fabrics made in accordance with the present invention become resistant to cross-staining during laundering or other process treatments. When this occurs, the resulting garment exhibits improved properties such as smoothing, being wrinkle-free, greater loft, improved moisture transport, and greater pick-up of cationic auxiliaries, such as softeners and biocides.
The invention described herein introduces a method in which colorfastness and dye transfer resistance become objectives for the manufacturers of cellulosic fabrics and no longer serve as objectives for the manufacturers of expensive detergents. The scope of the present invention encompasses a widely known household problem and brings about a practical solution to this problem. Resolving this problem is also an indicator of the other previously mentioned benefits such as greater absorption of softeners.
The present invention has multiple applications that reward both consumers and manufacturers with many advantages. The process of anionically treating the cellulosic fibers in white or light-colored fabrics prevents the fabrics from being cross stained while in the same bath with dark-colored fabrics. The treatment process also impedes the ability of colors on the same garment to bleed into one another. Similarly, by treating fibers to have an increased anionic charge, the fibers will resist cross-staining while they are being manufactured and heavily processed. The other benefits including comfort, softness, appearance, and aesthetic improvements are difficult to quantify, but are nonetheless important to the present invention.
In one particular application, the white pocket fibers and the undyed fill yarn in denim garments may be treated in accordance with the present invention so that they are not as stained by indigo dyes or other dark dyes present in the garments. As discussed above, in the past, garment manufacturers have had problems in keeping pocket liners white for the life of the garment, since such liners are typically made from undyed cotton fibers and blends which are easily cross stained. By treating pocket liners in accordance with the present invention, the pockets of a garment remain whiter even after repeated launderings, which greatly enhances the visual appeal of the garments.
The process of anionically treating cellulosic fibers in accordance with the present invention may also be applied to fibers and yarns used in carpeting. In particular, the process of the present invention is particularly well-suited for use with carpet materials made with cotton fibers. The treatment renders the carpet fibers extremely stain resistant to anionic compounds, dyes, and other coloring or staining agents. Charge repulsion results in greater loft and hence coverage.
Besides increasing the stain resistance of textile products containing cellulosic fibers, such as cotton fibers, the process of the present invention also produces other advantages. For instance, once treated in accordance with the present invention, garments have an increased attraction to cationic fabric softeners and bacteriocides, which may be used to treat the garments either during manufacturing or during regular laundering in the rinse cycle or in the dryer. Specifically, most fabric softeners and bacteriocides are cationically charged. Thus, by increasing the anionic character of fibers present in garments, a greater attraction is produced between the garments and the fabric softeners and bacteriocides. The levels of these ingredients can be controlled at higher levels. In addition, the softeners have improved resistance to laundering and lubricate the yarns to protect the garment from wear caused by abrasion.
As described above, the present invention is generally directed to a process for increasing the anionic character of cellulosic fibers in order to prevent cross-staining. Many different processes can be used to increase the anionic character of cellulosic fibers in accordance with the present invention. In the past, others have proposed various methods for increasing the anionic charge of cellulosic materials. As opposed to the present invention, however, these processes were not used for preventing cross-staining, but, instead, were used for other purposes.
In one embodiment of the present invention, the anionic character of cellulosic fibers is increased through a sulfation or sulfonation process. A variety of reagents are suitable for use in these processes.
For instance, sulfamic acid, a reagent normally found in powder form, can be used to achieve sulfation of cellulosic fibers. However, the use of sulfamic acid may lead to hydrolysis and yellowing of the fabric. Consequently, a neutral pH sulfamate is initially contacted with the fabric or fibers in order to protect the fabric or fibers from hydrolysis and yellowing. For example, in one embodiment of the present invention, the reaction product of sulfamic acid and a volatile amine is used. Thus far, such a reaction product has proved to be an effective and inexpensive sulfating agent for cellulosic fibers such as cotton fibers. However, it requires a relatively higher temperature to effect an adequate level of care.
As used herein, a volatile amine refers to an amine that will evaporate when the fabric is later cured. Examples of volatile amines that may be used in the present invention include methyl amine, ethyl amine, ammonia, and the like including mixtures of the above as well.
In one embodiment, ammonium sulfamate is used. The ammonium ion easily reverts to volatile ammonia when heated. Thus, the sulfating agent sulfamic acid is regenerated under mild conditions of minimal acidity to protect the cotton from hydrolysis.
In one embodiment of the present invention, when treating fibers and fabrics, the reaction product of sulfamic acid and a volatile amine can be added to an aqueous solution at a concentration of at least 20 grams per liter. For instance, in one embodiment, ammonium sulfamate is added to an aqueous solution at a concentration of 5-40 g/L and particularly at a concentration of 10-20 g/L. The concentration of course depends on the wet pick-up during application. Thus far, it has been found that adding over 40 g/L of the ammonium sulfamate to the aqueous solution adds no further benefit to the anionic treatment of the cellulosic fibers. In fact, the addition of too much ammonium sulfamate to the solution may start to induce excessive yellowing of the fibers and weaken the fibers.
In order for the above stated sulfation process to occur properly and to enable the cellulosic fibers to be anionically treated for resistance to cross- staining, urea, which may act as a co-reactant, can be introduced into the aqueous solution being prepared for the treatment. In addition, adding urea prevents yellowing of the fibers and protects the fibers during heat treatment. Urea can be added at a concentration from about 25 g/L up to about 100 g/L. In one embodiment, urea is added to the aqueous solution at a concentration of 25-75 g/L. Thus far, it has been found that using over 100 g/L of urea adds no further benefits to the cellulosic fibers when the urea and sulfamate ingredients are added separately to the formulation.
In general, a higher concentration of urea (50-75 g/L) should be used for certain cellulosic fibers such as 100% blended mercerized cotton fibers while a lower concentration of urea (30-50 g/L) can be used for other cellulosic fibers such as unmercerized cotton fibers. All of these recommendations apply to the case where urea and sulfamate are simply mixed together and not pre-formed into a complex.
Besides the derivatizing agent and urea, various other additives and ingredients may be included in the composition as desired. For instance, various additives can be included for either improving the process or for improving the final product. For example, in one embodiment, sodium borate (Na2B4O7) can be added. In particular, it has been discovered that sodium borate in small amounts is beneficial in further preventing yellowing of the fibers. For instance, sodium borate can be added to the composition in an amount up to about 8 g/L, and particularly in an amount from about 2 g/L to about 3 g/L.
In another embodiment of the present invention, ammonium phosphate may be incorporated into the aqueous solution in addition to urea. This component can be added at a concentration of approximately 5 g/L to replace 25 g/L of urea and maintain the same performance. The purpose of adding the ammonium phosphate is to act as a catalyst for the other reactants.
In another embodiment of the present invention, besides using a sulfamate, derivatising the cellulosic fibers is carried out by using the reaction product of epichlorohydrin and sodium bisulfite. The reaction product in this embodiment is a glycidyl sulfonate salt, which has the capability to act as a sulfonating agent unlike ammonium sulfamate which is a sulfating agent.
Various embodiments of a process for derivatising cellulosic fibers, particularly cotton fibers, in accordance with the present invention will now be described. In one embodiment, sulfation of the fibers is carried out using sulfating or sulfonating agents, such as ammonium sulfamate or sulfamic acid, in combination with urea. However, it was discovered that pre-generating the complex between urea and sulfamic acid improved the performance of this mixture. It should be understood, however, that various other sulfating or sulfonating agents may be used in accordance with the present invention in addition to other anionic modifying reagents and that the following description is for exemplary purposes only. In particular, it should be understood that the following concentration ranges and parameters can widely vary depending upon the particular application. For instance, such concentrations and parameters can change when treating carpet materials.
One embodiment of a process for anionically treating cellulosic fibers in order to render them resistant to cross-staining begins with adding the cellulosic fibers or fabrics to a solution bath. This aqueous solution bath can contain ammonium sulfamate and urea at concentrations of 5-20 g/L and 25-75 g/L respectively and can be at a temperature of from 60 to 90xc2x0F.
Well-prepared cellulosic fibers or fabrics are then contacted or padded with the aqueous solution for a short time. Such fibers require only a brief period of contact with the aqueous solution because of the high wet pick-up values (50-80% weight). After the fibers are contacted with the aqueous solution bath, the excess water and solution are abstracted by squeezing out the fibers or fabric.
The fibers are then dried at a temperature of from 150-200xc2x0 F. for 1-2 minutes. Next, the fibers are cured at a higher temperature (from 280-325xc2x0 F.) in order for the sulfation reaction to go to completion. During this heat treatment, the ammonia is volatilized and given off. Also during heat treatment, the sulfate ions that were released from the ammonium sulfamate reaction become bound to the cellulosic fibers, increasing the anionic character of the fibers.
The heat curing process can typically last up to approximately 5-10 minutes. This depends on the fabric construction and weight and in some cases xe2x80x9cflash curingxe2x80x9d at 400xc2x0 F.-425xc2x0 F. is sufficient (which can last for only a few seconds). The fibers are then rinsed at a temperature of about 100xc2x0 F. for 2 minutes and are neutralized with a sodium carbonate solution for 3-4 minutes. At the completion of this process, the anionic charge of the cellulosic fibers becomes permanently increased.
In addition to the embodiments described above, another improved embodiment of a process for derivatising cellulosic fibers, particularly cotton fibers, in accordance with the present invention includes the use of an aqueous solution of a pre-formed complex of a derivatising agent to anionically treat the fibers. This complex will afford the same result as before but at much lower cure temperatures.
The present inventors discovered that a complex formed from a derivatising agent can provide various benefits and advantages unknown in the prior art. For instance, the use of a pre-formed complex can allow curing at lower temperatures, thereby aiding in the efficiency of the overall process. In particular, lower curing temperatures can be realized with a pre-formed complex because the complex can form anions on cellulosic fibers at much lower temperatures than a simple mixture. Thus far, for instance, it has been found that the complex can be applied to cotton at a temperature as low as 240xc2x0 F., and particularly from about 240xc2x0 F. to about 300xc2x0 F.
In accordance with the present invention, one embodiment of a process for anionically treating cellulosic fibers using a pre-formed complex made from a derivatising agent in order to render the fibers resistant to cross-staining is described below. In particular, one embodiment of the present invention includes a pre-formed sulfamic acid complex to treat a cotton fabric. It should be understood, however, that various other sulfating or sulfonating agents may be used in accordance with the present invention in addition to other anionic modifying reagents and that the following description is for exemplary purposes only. In particular, it should be understood that the following concentration ranges and parameters can widely vary depending upon the particular application. For instance, such concentrations and parameters can change when treating carpet materials.
In general, a complex of the present invention is formed by mixing sulfamic acid with an amide of a carboxylic acid, such as urea. For instance, sulfamic acid can be mixed with excess urea in a mole ratio, of from about 1:3 to about 1:12 moles sulfamic acid to moles urea, and particularly from about 1 mole sulfamic acid to about 6 moles urea. The mixture is heated to 130xc2x0 F., without agitation, in the presence of a small amount of a catalyst, such as phosphoric acid, until the entire mass completely melts. Once the mass melts, it is thereafter mixed until a complex forms. The resulting complex can then be diluted with water. In one embodiment, phosphoric acid remains present in the form of ammonium phosphate in an amount of about 0.2 moles for every 1.0 mole of urea.
After the complex is formed, it is then applied to the cellulosic fibers or fabric, dried, cured and rinsed as described in the embodiments above. When curing a fabric treated with a complex of the present invention at higher temperatures, misting or smoking can often occur. For example, when a fabric treated with a urea-sulfamic acid complex is cured at temperatures of about 340xc2x0 F. or higher, a mist can result.
Such misting, often called xe2x80x9csmokingxe2x80x9d, typically occurs when organic mixtures that are partially soluble in water are heated so as to steam distill in the presence of boiling water. The low molecular-weight fractions of these mixtures, when deposited onto a fabric as part of a water solution, can be steam-stripped from the fabrics by the last remaining traces of water as the fabric is heated to dryness. Steam-stripping can disperse the organic particles into the atmosphere where they can then re-condense. These re-condensed particles form a visible mist.
In this regard, when urea-sulfamic acid complexes of the present invention are heated to higher temperatures, urea can be steam-stripped from the fabric to form a visible mist. Accordingly, to prevent such misting, additional amounts of ammonium sulfamate can be applied to compensate for any free urea present within the complex. It has been discovered that when additional ammonium sulfamate is added to the performed complex of the present invention, a non-volatile salt can form without any noticeable free urea mist. The salt effectively prevents misting by complexing the free urea. Moreover, both the urea and sulfamic acid within the salt remain fully functional in the anionic-generating process.
The amount of ammonium sulfamate added to the complex will generally depend upon the amount of free urea present within the complex. For most applications, less than a stoicheometric amount of ammonium sulfamate can be added to the complex in comparison to the amount of free urea. The ammonium sulfamate can be added as ammonium sulfamate or, alternatively, ammonia and sulfamic acid can be added separately. In one embodiment, ammonium sulfamate can be added in an amount such that the sulfamic acid present in the ammonium sulfamate is equivalent to the amount of sulfamic acid used to initially create the complex.
During the process of the present invention, only minor amounts of anionic ions need be attached to the cellulosic material in order to achieve the benefits and advantages of the present invention. For instance, the amount of sulfur attached to the cellulosic material during the process can be less than 0.5% by weight, particularly less than 0.05% by weight, and more particularly less than 0.005% by weight. Even at these small concentrations, it has been discovered that cotton materials will repel anionic agents and will attract cationic agents, such as softeners and bacteriocides.
As described above, the processes of the present invention permanently increase the anionic character of cellulosic fibers and fabrics in order to make textile articles resistant to cross-staining. For some applications, the fibers should be treated according to the present invention after a fabric or garment is formed, and preferably after the fabric or garment has been dyed. As such, the present invention can be viewed as a post-treatment process for post-treating formed fabrics and/or garments.
In alternative embodiments, however, the cotton fibers can be derivatised according to the present invention at other stages during the fabrication of the particular textile article. For most garments, such as shirts, blouses and the like, the anionic treatment takes place on the formed fabric before the fabric is cut and sewn into a particular item. In particular, preferably the fabric is treated after being dyed. For white garments, such as white shirts, the anionic treatment is carried out after the fabric has been bleached and treated with a colorless dye such as an optical brightener.
As stated above, the anionic treatment of the present invention is particularly designed for light or white colored fabrics, where cross-staining creates more of a potential problem. In fabrics and garments containing light colored areas and dark colored areas, such as striped or patterned fabrics, in one embodiment, the light colored areas can be treated according to the present invention by treating the yarn that is used to form those areas. Preferably the anionic treatment is carried out after the yarn has been dyed. For example, for denim fabrics and garments, preferably the white fill yarn is treated prior to being incorporated into the denim fabric. Alternatively, the fiber itself can be treated prior to being formed into the yarn.
Other garments that are particularly well suited for use in the process of the present invention include socks and other hosiery, pocket liners, and various undergarments. With respect to pocket liners, preferably the fabric that is used to make the pocket liners is treated prior to being incorporated into a garment. With respect to socks and undergarments, however, the yarn, the fabric or the completed product itself can be treated according to the present invention.
As described above, in addition to preventing cross-staining, the anionic treatment can also be used to facilitate application of softeners and bacteriocides. In general, the softeners and bacteriocides can be applied to the cellulosic materials after the derivatising agent has been applied.
Softeners that can be used in this regard include preferably cationic softeners or softeners contained within a cationic solution. By increasing the degree of anionicity of the cellulosic material according to the process of the present invention, it has been discovered that there is an increase in the rate of exhaustion and an increase in the amount of softener absorbed onto the surface of the material.
In the garment industry, there is great interest in producing garments with unique hand. Of particular interest is a hand that is very soft and buttery that gives cotton better drape. Normally, this is achieved with high levels of fatty and silicone derivatives and combinations. However, it is usually difficult to obtain a soft drape with softener alone. These disadvantages and drawbacks, however, have been overcome according to the process of the present invention.
Particular softeners that can be used according to the present invention include siloxanes such as aminosiloxanes, fatty amines, quaternary amines such as fatty quaternary amines, polysilicones and other silicones. For example, particular softeners that can be used in the present invention include BLUE-J ULTRALUX, which is a silicon fluid emulsified with non-ionic emulsifiers and is marketed by Sybron Chemicals, Inc. of Wellford, S.C. Another softener that may be used is TANASOFT HCA, which is a fatty amide and which is also marketed by Sybron Chemicals, Inc. Organomodified polydimethyl silicones that may be used include SILQUAT AT 5-52 and SILQUAT AT 5-49, both marketed by Silatech Corporation of Toronto, Ontario. Still another softener that may be used is KELMAR 1964, which is a silicone fluid and which is marketed by Kelmar Industries of Duncan, S.C.
Prior to being applied to cellulosic materials, such as cotton, in accordance with the present invention, the above softeners can be first combined with various other ingredients. For instance, in most applications, the softener will be combined in a solution or bath and applied to the cellulosic material. The bath can contain water, emulsifiers, and other solvents, such as alcohols. For instance, the above described organomodified polydimethylsilicones are typically combined with isopropyl alcohol prior to being applied to cellulosic materials.
In one preferred embodiment of the present invention, the softener composition selected is combined with one or more emulsifiers. It is believed that using particular emulsifiers, such as cationic or nonionic emulsifiers, facilitates application of the softener to cellulosic materials. Various emulsifiers that can be used include siloxane emulsifiers, such as amino siloxane emulsifiers (which can also be linear), quaternary amines such as fatty quaternary amines, soya amine quaternaries such as ethoxylated soya amine quaternaries, and ethoxylated alcohols. In one embodiment, the ethoxylated alcohol can include 6 moles of ethoxylate and wherein the alcohol has from about 9 to 11 carbon atoms in its chain. The emulsifiers can be combined with a softener in an amount from about 10% to about 50% by weight, and particularly from about 25% to about 45% by weight.
The softener solution can be applied to derivatised cellulosic materials in any suitable manner, such as spraying, dipping, or foaming. In one embodiment, the softener can be combined in a bath into which a fabric derivatised in accordance with the present invention is submerged. The bath can contain the softener in an amount up to about 50% by weight, particularly from about 1% to about 10% by weight, and more particularly in an amount from about 4% to about 6% by weight.
The bath can be maintained at room temperature or can be heated slightly, such as from a temperature of from about 80xc2x0 F. to about 150xc2x0 F. The pH of the bath will depend upon the particular circumstances. For most applications, however, the pH of the bath should be less 7.0, such as from about 4.5 to about 5.5. The derivatised cellulosic material can be submerged in the bath for a time sufficient for the softener to become bound to the material. For instance, the cellulosic materials can be placed in the bath for a time of from about 1 minute to about 20 minutes, and particularly from about 8 minutes to about 12 minutes.
Once the cellulosic materials are removed from the bath, the materials are dried and used as desired. In one embodiment, the materials can be dried at a temperature of from about 150xc2x0 F. to about 210xc2x0 F., and particularly from about 170xc2x0 F. to about 190xc2x0 F. for from about 20 minutes to about 60 minutes.
Besides fabrics and garments, however, the process can be used to treat fibers in other applications as well. For instance, as described above, the process of the present invention can be used to treat carpet materials, especially carpet materials containing cotton fibers, in order to increase the resistivity of the materials to staining by anionic agents, especially the red dye employed in the so-called cherry xe2x80x9cKool-Aidxe2x80x9d stain blocking test.
Textile products treated in accordance with the present invention have shown to be successfully resistant to cross-staining by anionic dyes. In particular, textile articles treated in accordance with the present invention are capable of resisting being stained when placed in a bath containing a cotton swatch dyed with 2% DR-79 red dye or 2% DBL-80 blue dye, which are commonly used anionic dyes, washed at 120xc2x0 F. according to AATCC IIA wash test specifications, rinsed clear and dried. Specifically, fabric swatches treated according to the present invention have been shown to have an AATCC gray scale rating of 4 to 5 after being contacted with the dyes as described above.
AATCC test method 61-1975, which includes reference to test IIA, is as follows:
1. Purposes and Scope
1.1 These accelerated laundering tests are designed for evaluating the washfastness of textiles which are expected to withstand frequent laundering. The color loss and abrasive action of five average hand, commercial, or home launderings with or without chlorine, are closely approximated by one 45-minute test. However, the staining effect produced by five average hand, commercial, or home launderings cannot always be predicted by the 45-minute test.
Staining is a function of the ratio of colored fabrics in the wash load and other end use conditions which are not always predictable.
2. Principle
2.1 Specimens are laundered under the appropriate conditions of temperature, bleaching and abrasive action such that the desired loss of color is obtained in a conveniently short time. The abrasive action is accomplished by the use of throw, slide, and impact, together with the use of a low liquor ratio and an appropriate number of steel balls
3. Apparatus and Materials
3.1 Laundering-Ometer or similar apparatus for rotating closed containers in a thermostatically controlled water bath at 42 rpm
3.2 Stainless steel cylinders, 9xc3x9720 cm (3xc2xdxc3x978 in)
3.3 Adapter plates (for holding 9xc3x9720 cm (3xc2xdxc3x978 in.) cylinders on Launder-Ometer shaft)
3.4 Stainless steel balls
3.5 Flatiron
3.6 Multifiber test fabric No. 10
3.7 Cotton fabric 80xc3x9780, bleached, desized
3.8 AATCC Standard Detergent WOB (without optical brightener)
3.9 AATCC Standard Detergent 124 (contains optical brightener)
3.10 Acetic acid, 28%
3.11 Water, distilled
3.12 Sodium hypochlorite
3.13 AATCC Chromatic Transference Scale
3.14 Gray Scale for color Change
3.15 Gray Scale for Staining
4. Test Specimens
4.1 The size of the specimens required for the test is as follows: 5xc3x9715 cm (2xc3x976 in.)
4.2 One specimen is needed for each container
4.3 To determine staining multifiber test fabric should be used.
4.4 Prepare pieces with a 5 cm (2 in.) square of multifiber cloth sewed or stapled along one 5 cm (2 in.) edge of the test specimens and in contact with the face of the material. Attach so that each of the 6 fiber stripes along the 5 cm (2 in.) edge of the specimen. It is recommended that knitted fabrics be sewn or stapled at the four edges to equivalent size pieces of 80xc3x9780 bleached cotton fabric to avoid rolled edges and to assist in obtaining a uniform test result over the entire surface.
5. Procedure
5.1 Table I summarizes the conditions of the test.
5.2 Adjust the Launder-Ometer to maintain the designated bath temperature. Prepare the required volume of wash liquor. Preheat this solution to the prescribed temperature.
5.3 The tests are run in 9xc3x9720 cm (3xc2xdxc3x978 in.) stainless steel cylinders.
5.3.1 Place in the cylinder the amount of detergent solution as designated in Table 1.
5.3.2 Add the designated number of stainless steel balls to each container and clamp the cover. Fasten the 9xc3x9720 cm (3xc2xdxc3x978 in.) containers horizontally in the adapters on the rotor of the Launder-Ometer in such a manner that when the containers rotate, the covers strike the wafer first. They are also arranged so that an equal number of containers is on each side of the shaft.
5.4 Start the rotor and run for not less then two minutes to preheat the containers.
5.5 Stop the rotor and with a row of containers in an upright position, unclamp the cover of one container, enter a well-crumpled test specimen into the solution and replace the cover, but do not clamp it. Repeat this operation until all the containers in the row have been loaded (cover clamping is delayed to allow equalization of pressure). Start the Launder-Ometer and run at 42 rpm for 45 minutes.
5.6 The rinsing, souring extraction, and drying methods are the same for all the tests.
Stop the machine, remove the containers and empty the contents. Rinse each test specimen twice, in beakers, in fresh 100-ml baths of water at 40xc2x0 C. (150xc2x0 F.) for one-minute periods with occasional stirring or hand squeezing. Sour in 100 ml of a 0.014% solution of acetic acid (0.05 ml of 28% acetic acid per 100 ml of water) for one minute at 270xc2x0 C. (80xc2x0 F.). rinse again for one minute in 100 ml water at 27xc2x0 C. (80xc2x0 F.). Hydroextract or pass the test specimens between wringer rolls to remove excess moisture. Dry by pressing with an iron (135xc2x0 C.-150xc2x0 C.) (275xc2x0-300xc2x0 F.) with the fabric uppermost and in contact with the face of the test specimen.
6. Interpretation of Results
6.1 The conditions in these tests give results which correlate with the results of five average home or commercial launderings. These are accelerated tests, and in obtaining the required degree of acceleration some of the conditions, such as temperature, were purposely exaggerated. These tests are satisfactory consumer end-use tests, and the correlation with average laundry practice is given in the following section on Evaluation.
7. Evaluation
7.1 This test is designated for evaluating the washfastness of fabrics that are expected to withstand repeated low-temperature machine washing in the home or in the commercial laundry. Specimens subjected to this test should show color damage similar to that produced by five commercial launderings at 38xc2x0 C. (100xc2x0 F.) or by five home machine launderings at medium or warm setting in the temperature range of 38xc2x0 C. (100xc2x0 F.).
8. Evaluation Method for Staining
8.1 Staining can be evaluated by means of the AATCC Chromatic Transference Scale or the Gray Scale for Staining. The means should be indicated when reporting the test results.
Class 5xe2x80x94negligible or no staining.
Class 4xe2x80x94staining equivalent to Row 4 on the AATCC Scale or Step 4 on the Staining Scale.
Class 3xe2x80x94staining equivalent to Row 3 on the AATCC Scale or Step 3 on the Staining Scale.
Class 2xe2x80x94staining equivalent to Row 2 on the AATCC Scale or Step 2 on the Staining Scale.
Class 1xe2x80x94staining equivalent to Row 1 on the AATCC Scale or Step 1 on the Staining Scale.
Because of the use of sulfamate in the application of the resins, the anionic character of the fibers is also increased. Thus, the fibers become both wrinkle and stain resistant.